Control system



May'=!4,1929. immm 1,713,208

CONTROL SYSTEM Filed June 19, 1928 Inventor:

do '1' Yu ama by wag His Attorney Patented May 14, 1929.

UNITED STATES JUJI YUYAMA, OF EBARAGUN TOKYOFU,

JAPAN, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CONTROL SYSTEM.

Application filed June 19, 1928, Serial No. 286,656, and in Japan July 5, 1927.

My invention relates to control systems and particularly to a system for starting syn-' when the machine has accelerated to approximately synchronous speed,'the .field winding of the machine is excited with direct current to pull the machine into synchronism and then normal operating voltage. is impressed upon the armature winding.

One object of my invention is to provide an improved arrangement for controlling the transfer from the starting connections or the armature winding of the machine to the running connections after the motor has accelerated to approximately synchronous speed and the field winding has been excited with direct current to pull the machine into synchronism.

My invention will be better understood from the following description taken in connection with the accompanying drawing which is a diagram of a control system for a synchronous machine and its scope will be pointed out in the appended claims.

Referring to the accompanying drawing, 1 represents a synchronous motor comprising an armature winding 2 and a field winding 3. In order that a relatively low voltage may be impressed upon the armature winding 2 to start the motor I provide a compensator a which is connected to a suitable source of current, such as an alternating current supply circuit, 5 and a starting switchfi which when closed connects the armature winding 2 to the low voltage terminals of the compensator a. Normal operating voltage is arranged to be impressed upon the armature winding 2 by the closing of a. running switch 7 which when closed connects armature winding 2 directly to the supply circuit 5.

The field winding 3 is arranged to be supplied with direct current from a suitable source of current, such as an exciter 8, when a field switch 9 is closed. As shown in the drawing this field switch 9 is manually controlled but it is obvious that any suitable control means, examples of which are well known in the art, may be provided for automatically closing the switch 9 at the proper time during the starting of the motor. For regulating the amount of exciting current supplied to the ield winding 3 by the exciter 8 I provide a suitable regulator 10 which is arranged to maintain the field current constant at a predetermined value. As shown in the drawing the regulating means comprises a motor operated rheostat 11 and a current responsive relay 12 which is responsive to the current flowing through the field winding 3 and whichis arranged to cooperate with the control relays l3 and 14: so as to operate the motor operated rheostat 11 in such a manner that the proper amount of resistance is in the circuit oi the field winding to maintain the field current at the desired value. p

I In accordance with my invention I provide an arrangement whereby the starting switch 6 is opened and the running switch 7 is closed when the current through the field winding 3 remains at a predetermined alue for a predetermined length of time. In the arrangement disclosed in the drawing this result is accomplished by means of the timing relay which is arranged to be energized whenever the current responsive relay-l2 is in a position to eli'ect the operation of either or the control relays 13 and 14. \Vhenever the current responsive relay 12 is in a position in which it does not efiect the operation oi either of the control relays 13 and 14 the time relay 15 is d-eenergized and it it remains deenergized for a suificient length 01" time it efiects the operation of a transfer relay 16. The transfer re lay, in turn, effects the opening of the starting switch 6 and the closing of the running switch '4'.

In order to prevent the transfer relay 16 from effecting the transfer from the starting to the running connection during the starting operation and before the field switch 9 is closed a timing relay 1'? is provided which controls the circuit of the transfer relay 16 so that this relay can only operate after the field switch 9 has been closed for a predetermined "length of time. 18 and 19 represent suitable control switches for controlling the synchonous motor.

The operation of the arrangement show in the drawing is as follows: Preferably before the motor is started, the control switch 19 is closed for a short time so that the circuit or the control relay 14 will be completed across a suitable control circuit 20 to cause the motor operated rheostat to be operated to insert resistance in the field circuit of the L is impressed uponthearmaturewinding. The -motor then starts as an :induction'inotor and P16. Aftertl e fieldswitch 9 rent responsive relay 12 operates to energize; 7 either the. control relay 1 3 or the control re lay 14 so as to cause the motor operatedrheo- V stat to be operated toinaintainlthe lield,

When it is desired to start the meter the The closing oi the control switch 18 completes through the contactsQl of the transfer relay lfi a circuit,

control switch 18 is closed.

torthe starting switch 6 across the control circuit 20. The closing, of; the "starting: sivitchfi iconnects the armature winding 2 of the motorl to the low voltage terminals of the compensator 1 sotliat ai'e'latively low voltage up to approximately synchronous speed.

. After the inotorhas reached substantially synvclironolesspeed the field switch Qisfclosed so that the field Winding .zthe eiiciterg. "l.h e closing of the auxiliary. contacts 22 of the field switch Sronnects the,

"coilgot the time relay l'iacross the control u is connected to circuit 20. After a predetermined time the time relay 17 closes its contacts 23 which are; in thecircuit of the rans r e y. 6. lore these contacts aro closed, however, the relay 1 5 is energizedsothat 113 0136118 its'con .tacts. .24. in, h c cu t ofr he. nsfe re y current of the/ 11101 93 at fa predetermined {trol relay 153 is, completed from one side of s vitchlS, auxiliary contacts 22 ofthelfield leng itii e Ti V a field Switch 9 is closed the. r layjlo operates switch 9, coil of relay contacts 25 of the ,current relay,12 coil of relay 13, contacts 26 ,7 of relay lit to theother'sideof the control circuit. lVhent-he field currentis above thepredetermined value the contacts 27 oi the current relay 1 2 are'closed so thattlielrelay 15 and control relay arecoiinected in series. H Thetimerelay15 is of any suitable construc' tion so that when it is energized it imin edi atelyopenslts contacts 24 but does not close I i its contacts 24 untila tterthel coil of the re"- lay has been deenergiged a predetermined ieretore as soon as the to open its contactsfl l and maintains these I side of the control circuit; fllheenergization contacts openu itil thefield current remains constant at the predetermined;value for predetermined length of time. When the re lay 15 closes its contacts 24' after the field" switch .9 is closed a circuit is completed for ,j 'the transfer relay-16., This circuit is from one, side of the control circuit 20 through contacts 2810i time relaygl'fl contacts 24 of time relay lfg, coil of relay tothejother of the relay 16 effects the opening of the coii tacts 21 so that the starting switch 6 is open is closed the our} the armature winding-'21s disconnected ti 1 the low voltage terminals of the cointacts Q8 vvhi cliai'e in the circuit of the closing coil of the runn ng switch 7. This circuit is from. "one side of the control ClI'CUlt 20 through the control switch 18, contacts '28 of the transfer relay iaemsing coil of switch 7 totheiother side of thecontrol circuit. The energization oi tl1 ClO$111g coil of thesiwitch 7 closes the SW1tCl17 "so that,theiarinature fpeiisator ta nd effects the closing'of'thecon- Winding 2 is connecteddirectly to the source.

of current 5. z

,It will be obse rod that in accordance With my inigention :tlie'trans'fer' iroiii the starting to the running connectio nfis" fi'ected" only after the field curreiit has remained constant at lengthottime. I

statutes shown and described "iii; invention as applied to a particular siysteiiiand asem bo'dying various devices diagrammatically I indicated, chan es and inodi'ficatioi'is'will be obvious to I those I skilled in the are "and I,

felectricniachine havii'i g 'afield winding, a e value, Il/Vhen the field current is belovv the predeterminedyal ie thec rcuit for the conr el'ati'velylow alternating current voltage connected to. said machine, aisource againeans for s 'ipplying' e'iciting fcurrent to said field i ding, regulating means fofcontrolling the amount of exciting j current in While i have in neonat s with the patent v apredetermined value for a predetermined .UU. i Q BMW;

ror.ieiaaviyinghj lte'rnating current volt- .the control circuit20 through the control tively 10w voltage source and thec'oniiection age source .When' the exciting current remains constant at'a' predetermined value for a predeterminedtime. I i j" I f 2; In" combination, a synchronousdynamo electric machineliaviiigafield Winding, a source of relatively low alternating current coi'i'nected to said machine} a 'sourc'e "of relativ'ely high alternating current voltage, a source of exciting current; "switching means for connecting said xciting'awiem source to said "tie'ld' 'wviriding, means operative in respoi'ise' tothe' closing of saidswitching'means for the amountof .currentiiisaid field ivinding and 'iiiean's' coiitrolledby said regulating means 'or efiecting the disconnec tion of said machine from s aidrelatively low voltage "so es and the connection of said machine to saidrelativelyhigh voltage source when the exciting current remains constant "at a predetermined Value for a predetermined time.

3. In combination, a synchronous dynamo electric machine having a field Winding, a source of relatively low alternating current voltage connected to said machine, a source of relatively high alternating current voltage, a source of exciting current connected to said field Winding, and means responsive to the exciting current supplied to said machine by said source of excitation for regulating the exciting current and for efiecting the discon nection of said machine from said source of relatively low Voltage and the connection of said machine to said source of relatively high voltage.

4:. In combination, a synchronous dynamo electric machine having afield Winding, a

source of relatively low alternating current voltage connected to said machine, a source of relatively. high alternating current voltage, means for supplying exciting current to said field winding, regulating means responsive to the exciting current of said machine for maintaining the exciting current at a predetermined value and timing means controlled by said regulating means for elfecting the disconnection of said machine from said source of relatively low voltage and the connection of said machine to said source of relatively high voltage.

In Witness whereof, I have hereunto set my hand this twenty-eighth day of May, 192-8.

JUJI YUYAMA. 

